Britain's inner cities will flourish only if the middle classes are wooed back to live in them, according to the man charged by the government with stimulating an urban renaissance.

Lord Rogers of Riverside, the architect who in 1998 was appointed head of the government's Urban Task Force, is to unveil a new blueprint for the future of Britain this week that will see the middle classes placed firmly at the centre of urban life once more.

'Middle-class families, primarily those that are white, are moving out of the cities in search of better schools, less congestion and safer environments,' Rogers said from his New York office last Friday.

The danger of the continuation of the exodus, Rogers believes, can be seen in the worrying examples of Paris or New Orleans, where whole neighbourhoods are now made up of separate ethnic groups. 'There are lessons to be learnt from Paris. We need to work out how to welcome minority groups, not ghettoise them,' Rogers said.

The Bridget Jones brigade, he believes, are ripe for wooing. 'A vast number of people are single,' he said. 'They're the ideal target for cities and we need to encourage more of them to come back.' The problem, he believes, is that today's cities are simply not offering the sort of housing this most discerning of socio-economic groups desires. 'How do you encourage these people to come back to the cities? You can't force them. The quality has got to be good enough.' And this, Rogers believes, is not the case. 'The quality of design in Britain is, in general, abysmal,' he said. 'If you take a boat down the Thames, you will be shocked by what we're doing with this most beautiful river. It should be comparable with Amsterdam, but it's not.'

Rogers is especially critical of the Thames Gateway, Europe's most ambitious housing project, which will see a city the size of Manchester rolled out to the east of the capital. Much of the blame for poor design he lays at the door of Britain's burgeoning number of quangos, notably the regional development agencies, which are charged with stimulating city regeneration.

'The reason we've got such poor design standards is that the delivery process is extremely bureaucratic,' he said. 'There's a plethora of overlapping organisations. There should be a single regeneration company. Instead we have body upon body with very little clarity in terms of quality.'

In Rogers' vision of the future, Britain's cities are dramatically more compact than they are now. Planners build upwards towards the sky, they fill in gaps and spaces, they build over derelict sites.

The model could be New York, whose vitality Rogers credits to its high-density housing. He is also full of praise for the Spanish city of Barcelona. 'The densest city in Europe is Barcelona,' he said. 'If I had to say what was the best city in terms of regeneration, it would be Barcelona.'

He believes significant progress has been made in making Britain's cities more compact, but insists more needs to be done. 'If we're going to have that vitality in cities we need higher density. We've gone from 25 dwellings per hectare in 1997 to about 40 dwellings per hectare today. That's a big increase, but way below our continental European cities.' In contrast, for example, some parts of Barcelona and Paris boast 400 dwellings per hectare.

Rogers' blueprint, which will be unveiled on Tuesday at a conference hosted by the Centre for Cities, a new unit within the Institute of Public Policy Research, provides solid demarcation lines between city and country. The emphasis is on regenerating brownfield sites, not greenfield ones, and Rogers is quick to defend the current government against many of the charges that it is bulldozing over Britain's green and pleasant land.

'It has had considerable success. Around 55 per cent of building was on brownfield sites in 1997. It's now hitting over 70 per cent and in places like London it's over 90 per cent. That's a fantastic improvement. This is the first government anywhere that I know of which really believes that people should return to the cities rather than leave.'

Architects and planners have also played their part in provoking the exodus, Rogers argues. He accuses some of his peers of 'anti-urbanism' for trotting out concepts such as 'new towns' rather than focusing on regenerating inner cities.

But while Rogers' emphasis on design and quality will strike a chord with many middle Britons, Dermot Finch, Director of the Centre for Cities, suggests this will go only so far in attracting people back into urban areas. The Institute of Public Policy Research wants the government to devolve a raft of powers to cities, including giving them the ability to raise revenues. This, Finch argues, would help to reduce the nation's reliance on London.

'We have a very London-led economy. We want to see other cities punch their weight more, which they're not doing at the moment,' Finch said.

There is friction, too, within the Urban Task Force, with not all members agreeing with Rogers' recommendations. Professor Peter Hall, one of the country's leading authorities on the planning system, believes moves to increase further densities of new homes will create a housing crisis.

Hall is concerned that any move to cram more people into urban centres will slow down the delivery of much-needed new homes to house those priced out of the South East, and create social problems. Nevertheless, Rogers argues the government's policies - most based on the recommendations of the task force - have yielded some demonstrable success. Last week he gave a speech at Harvard University where he talked about the regeneration of inner-city Manchester.

'In 1990 there were 90 people in the heart of Manchester. Today there are 25,000 residents. That's a true urban renaissance,' Rogers said. It's a comparison he is likely to refer to again in the coming months. The Olympics are just seven years away, while the Thames Gateway continues to evolve, to varying degrees of success. New policies are evolving to redress the North-South divide. Meanwhile the housing crisis worsens and more and more people cannot afford a home.

Rogers, now the Mayor of London's chief adviser on regeneration issues, believes such factors have prompted an urgent need to suck people back into Britain's inner cities.

'My major concern is that we must get the quality of buildings and public spaces to a standard which is better than Barcelona, that's the gold standard. But I am worried. We have little time.'